The present invention relates to an ink tank for supplying ink to a print head, and to a recording apparatus with employment of this ink tank.
Conventionally, as the ink supply mechanism employed in the recording apparatus for recording by ink, as described in, for example, Japanese Laid-open Patent Application No. 63-87242, and U.S. Pat. No. 5,025,271, such an ink supply mechanism has been proposed that the porous member is arranged within the ink tank, one end of this porous member is coupled via the filter to the print head, and the other end thereof is provided with the air intake port. In the ink supply mechanism described in this publication, compression force is given to the foam corresponding to the porous member within the vessel by the tab. However, such an arrangement has a problem that the capillary force of the foam would be increased at the depression unit of the foam by the tab, and the ink may readily remain in the foam. Also, there is a design limitation such that to apply the proper compression force, the above-described arrangement could not be realized unless the ink dipped member per se is the elastic member.
Another conventional technique is described in, for instance, Japanese Patent Publication No. 5-23954. That is, in this ink tank, the projection portion is formed which constitutes the space between the inner wall surface of the ink tank and the ink dipped member. Furthermore, this ink tank owns the means for communicating this space with the atmosphere. However, when the space is formed by the projection unit, the capillary vessel force of the ink dipped member would be similarly increased at the contact point between the projection unit and the ink dipped member. Thus, there is another problem that the ink may readily remain in the ink dipped member.
Furthermore, Japanese Laid-open Patent Application No. 6-15837 discloses the means having the projection portion around the atmospheric communication port in order that the ink does not dip into the atmospheric communication port. However, also in this case, the capillary vessel force of the porous member would be increased at the contact point between the projection portion and the ink-dipped porous member. Thus, there is a problem that the ink may readily remain in the porous material. Moreover, the porous member concaving with the projection portion may easily form the unwanted space between the inner wall surface of the ink tank and therewith. Accordingly, there is a risk to release negative pressure in the ink tank.
Further, the present invention relates to an ink tank which has an atmospheric communication hole and introduces air into the tank, and to an ink-jet recorder equipped with this ink tank.
In an ink-jet recorder, ink is stored in an ink tank, and the ink is supplied to a head corresponding to the amount of ink consumed by recording. The ink tank introduces air into the tank corresponding to the amount of ink supplied to the head through an atmospheric communication hole to thereby regulate an ink pressure to be exerted on the head. In the case of an atmospheric communication hole formed simply in a plane plate, in the event of physical shock or changes in environmental changes, ink seeps from an ink-impregnated member which holds ink inside the ink tank, and the thus-seeped ink leaks out of the ink tank through the atmospheric communication hole.
One example of the construction of an existing ink tank is proposed in, e.g., the Unexamined Japanese Patent Application Publication No. Hei 7-32063. In this ink tank, ink is held by an ink-impregnated member, and a rib is formed in the ink tank in order to prevent the ink-impregnated member from directly entering the atmospheric communication hole, so that an air layer is eventually formed above the ink-impregnated member.
However, the ink tank having the foregoing construction encounters another problem, i.e., the seeping of the ink from the atmospheric communication hole after having splashed into the air layer around the ink-impregnated member. For this reason, the amount of ink to be filled in the tank cannot be increased. Further, since the ink-impregnated member is pressed by the rib, the density of the thus-pressed area of the ink-impregnated member increases, so that ink remains in that area. As a result, it becomes impossible to fully use out the ink held by the ink-impregnated member. Moreover, in order to prevent the ink-impregnated member from directly entering the atmospheric communication channel, a large air layer becomes necessary, which in turn hinders the effective utilization of the inside of the ink tank and results in an increase in the size of the ink tank or a reduction in the amount of ink to be filled.
A communication plate which forms a plurality of cavities disclosed in the Unexamined Japanese Patent Application Publication No. Hei 8-39821 is attached to the outside of an ink tank in order to prevent the leakage of ink and the mixing of colors. The communication plate attached to the outside of the ink tank makes the ink tank bulky correspondingly. Further, since an ink-impregnated member is supported by a rib in the ink tank, space must be ensured above the ink-impregnated member, making it difficult to reduce the size of the ink tank.